Lab talk

Sep 14, 2010

Vibrating edge cuts nanopatterns from viscoelastic block

Canadian researchers at McMaster University led by Dr Shiping Zhu have developed a new nonlithographic nanofabrication method based on "controlled chattering". Chatter, resulting from undesired vibrations of a workpiece and/or cutting tool, typically leads to unwanted artifacts in machining, and great efforts are often made to eliminate the problem.

Recently, Zhu and his colleagues have demonstrated that chatter can be put to good use and have exploited the effect to generate well-defined nanopatterns. The researchers use an ultrasonication diamond knife to intentionally invoke chatter during microtomy sectioning, which makes the process manageable.

As shown in the image, the oscillatory vibration of the cutting knife generates uniform, wavy patterns on both thin sections and block surfaces. Patterning can be fine-tuned by adjusting cutting speed and oscillation frequency.

The smallest structure made by this method was 36 nm and it is very easy to increase the size to the micrometre level. The technique is applicable to a variety of materials with suitable viscoelastic properties. In addition, the process allows wavy patterns to be fabricated on slightly curved surfaces, which is difficult or infeasible to achieve by conventional photolithography.

To summarize, this simple, one-step non-lithographic "cutting-edge" technology is robust and clean, involves no chemicals, and is easy to scale up for long-range and large-area patterning.

About the author

This work is a "by-product" of a Polyshell project aimed at developing block copolymer additives for anti-scratching acrylic plastics. It was supported by the Centre for Materials and Manufacturing (CMM), Ontario Centres of Excellence (OCE). Ms Helen Gu is a PhD candidate and she performed most of the cutting and characterization experiments, assisted by Dr Junwei Zhang – a postdoctoral fellow. Dr Santiago Faucher is a former PhD candidate in the group who participated in discussion and analysis. Dr Shiping Zhu is team leader and supervised the research. He holds the Canada Research Chair in Advanced Polymerization Technology and is Chair of the Department of Chemical Engineering at McMaster University. Mr Ross Bradsen of OCE also provided helpful input and assistance in this work.